1. Field of the Invention
The invention relates to a fingerprint recognition technology, and more particularly, to a fingerprint enrollment method and a fingerprint enrollment apparatus.
2. Description of Related Art
Fingerprint recognition is an important part in Biometric Recognition System. Features of the fingerprint can be classified into three levels including level 1, level 2 and level 3. Level 1 refers to overall geometrical forms (overall shapes of line) of the fingerprint which are macroscopically recognized, such as left loop, right loop, double loop and so on. Level 2 refers to features of lines on the fingerprint which are microscopically recognized, such as ending, bifurcation, eye, hook and so on. The features of line are collectively known as minutiae. Level 3 refers to in-depth features of lines on the fingerprint which are microscopically recognized even further, such as pores and so on.
A fingerprint sensor may be disposed in a small electronic apparatus (e.g., a hand-held cellular phone) for information security. In stage of a fingerprint enrollment, the conventional electronic apparatus performs the fingerprint enrollment according one single capture of a fingerprint image captured by the fingerprint sensor in order to obtain an enrolled fingerprint template. After the finger enrollment is completed, the conventional electronic apparatus can then provide functions for a fingerprint verification. The so-called “fingerprint verification” refers to a comparison of a level of similarity between an enrolled fingerprint and a to-be-tested feature so that whether the same fingerprint is captured can be determined. The functions for the fingerprint verification are applicable to border control, civil identification of offender status, business and home access control, public safety, data access, mobile communications, mobile payment or other information security applications.
The fingerprint sensor may be disposed in the small electronic apparatus (e.g., the hand-held cellular phone). However, due to the restrictions in volume/area of the small electronic apparatus, the fingerprint sensor of the small electronic apparatus is generally a small area sensor. A sensing area of the small area sensor may be smaller than an area of the finger. Because the fingerprint image captured by the small area sensor is only a partial fingerprint of the finger, an area of the enrolled fingerprint template can be fairly small (i.e., the template has a small quantity of feature points). The fingerprint verification may fail frequently if the area of the enrolled fingerprint template is fairly small (i.e., which leads to the small quantity of feature points in a finger template). The user may need to accurately press on a pressed region originally set in the enrollment in order to pass the fingerprint verification. Furthermore, the safety is lowered since the fingerprint template has only the small quantity of feature points.